1. Field of the Invention
This invention relates to aquarium maintenance, specifically an active culture of Nitrosomonas for oxidizing ammonia.
2. Discussion of Prior Art
Nitrosomonas is a genus of bacteria in aquaria which oxidize ammonia. A toxic waste product of animals, ammonia accumulates causing injury or death to aquarium inhabitants.
When fish or other animals are added to an aquarium, a small number of Nitrosomonas are carried with them and introduced into the aquarium. As aquarium animals produce ammonia, the Nitrosomonas begin to oxidize it into nitrite.
Ammonia is produced faster than the rate at which the small number of Nitrosomonas can oxidize it. Ammonia levels rise to toxic levels, killing or injuring aquarium inhabitants until a sufficiently large population of Nitrosomonas develops to keep ammonia levels at or near zero.
Unlike many bacterial species, Nitrosomonas do not have the ability to produce spores. Many bacterial species are capable of producing dormant spores which are resistant to adverse environmental conditions.
When starved of ammonia, under certain conditions, the vegetative Nitrosomonas cell is capable of becoming dormant and surviving in this state without ammonia, its only food and source of energy, for years. While dormant, however, the cell is not resistant to adverse environmental conditions. While dormant the Nitrosomonas cell is much more sensitive to adverse conditions such as chemical insults and exposure to light.
Nitrosomonas are relatively slow to reproduce compared to most other bacterial species. To accelerate the establishment of the needed population of Nitrosomonas in an aquarium, many commercial products claiming to contain live Nitrosomonas are available. It is claimed that the addition of these products will prevent toxic ammonia accumulation.
Heretofore, these products suffer from a number of disadvantages:
(a) If the product is a dried or freeze dried culture little or none of the Nitrosomonas cells survive. This type of processing kills all or almost all Nitrosomonas cells. Adding dead cells increases the amount of organic material available for decomposition thereby increasing the amount of ammonia produced. Adding only a few live cells which might survive this type of processing does not have an appreciable effect on reducing ammonia accumulation.
(b) If a liquid culture of Nitrosomonas is packaged in a closed container with an ammonia (i.e. energy) supply present cells may die as a result of oxygen starvation.
(c) If a liquid culture of Nitrosomonas is packaged in a closed container with other species of bacteria present, particularly anaerobic varieties, Nitrosomonas cells will die. Death results from the toxic effects of the waste products, such as hydrogen sulfide, produced by other species of bacteria.
(d) If a liquid culture of Nitrosomonas remains suspended in its own culturing media cells will die as a result of exposure to its own waste products.
(e) If a liquid culture of Nitrosomonas is not maintained under aseptic conditions, cells can die as the result of the waste products of other organisms, the action of organisms which can utilize Nitrosomonas as a food, and the action of organisms which can use Nitrosomonas as a host.
(f) Most of the waste products covered in (c) through (e) are also toxic to other aquarium inhabitants. The addition of these cultures to an aquarium can result in the addition of toxic chemicals causing injury or death to aquarium inhabitants.
(g) If a liquid culture as described in (b) through (e) above, is kept under refrigeration, the Nitrosomonas cells can remain alive for a limited time. The limited shelf and high cost for maintaining temperature control has restricted the use of such products.
(h) Any Nitrosomonas cells which survive the packaging procedures described in (a) through (e) and (g), above, will be in a state of metabolic dormancy. When added to an aquarium system, dormant cells require several days before metabolic activity and the ability to oxidize ammonia returns, assuming ammonia is present. During this "lag" period, ammonia levels accumulate to toxic levels killing or injuring aquarium inhabitants.